To evaluate the inhibitory effects of drugs on the growth of Babesia gibsoni, relative quantification real-time PCR method was developed in this study. The 18S rRNA gene was used as a target gene for the 2–ΔΔCt method analysis. Additionally, chicken RNA was added to the parasitized blood before total RNA extraction. The chicken β-actin gene was selected as an internal control gene for the 2–ΔΔCt method analysis. The 100 µL parasitized blood samples with different percentages of parasitized erythrocytes (PPEs) (3%, 1.5%, 0.75%, 0.375% and 0.1875%) were prepared for relative quantification of B. gibsoni. Regression analysis results revealed significant linear relationships between the relative quantification value and parasitemia. 18S rRNA gene expression was significantly decreased after treatment with diminazene aceturate and artesunate in vitro drug sensitivity test. This result suggested that this relative quantification real-time PCR method can be used to evaluate the effects of drug inhibition.

Toxoplasma gondii, a ubiquitous pathogen that infects nearly all warm-blooded animals and humans, can cause severe complications to the infected people and animals as well as serious economic losses and social problems. Here, one local strain (TgPIG-WH1) was isolated from an aborted pig fetus, and the genotype of this strain was identified as ToxoDB #3 by the PCR RFLP typing method using 10 molecular markers (SAG1, SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, C22-8, C29-2 and Apico). A comparison of the virulence of this isolate with other strains in both mice and piglets showed that TgPIG-WH1 was less virulent than type 1 strain RH and type 2 strain ME49 in mice, and caused similar symptoms to those of ME49 such as fever in piglets. Additionally, in piglet infection with both strains, the TgPIG-WH1 caused a higher IgG response and more severe pathological damages than ME49. Furthermore, TgPIG-WH1 caused one death in the 5 infected piglets, whereas ME49 did not, suggesting the higher virulence of TgPIG-WH1 than ME49 during piglet infection. Experimental infections indicate that the virulence of TgPIG-WH1 relative to ME49 is weaker in mice, but higher in pigs. This is probably the first report regarding a ToxoDB #3 strain from pigs in Hubei, China. These data will facilitate the understanding of genetic diversity of Toxoplasma strains in China as well as the prevention and control of porcine toxoplasmosis in the local region.